Process for distilling sulphuric acid



G. BAUM.

PROCESS FOR DISTILLING SULFHURIC ACID.

APPLICATION FILED JUNE 11. 1921.

qwmga PatentedJune 6,1922,

carr es stares PATENT oFFicE.

GUSTAV BAUM, OF CARINTI ITA, AUSTRIA, ASSIGNOR TO THE FIRM CHEMISCHE FABRIK WEISSENSTEIN GESELLSCHAFT M. B. 3-1, 013: CARINTHTA, AUSTRIA, A

COMPANY OF AUSTRIA.

PROCESS FOR DISTIlDLING SULP HURIC ACID.

Specification of Letters Patent. Patented June 6, 1922.

' Application filed June 11,1921. Serial No. 476,901.

To all whom it may concern:

- zen of the Republic of. Austria, and residing at Weissenstein, ob der Drau, Carinthia, Austria, have invented certainnew and useful Improvements in a Process for Distilling Sulphuric Acid (for which an ap lication for patent was filed in Austria ay 21, 1920) and I- do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which. form a art of this specification.

' The distillation of technical sulphuric acid especially for the purpose of producing pure acid has been hitherto .a very small scale process since glass retorts and quartz vessels have alone been practicable for the process and these materials do not lend themlining, have not found a footing in practice, as the hair-cracks in the enamel expose the material underneath.

Although rogress in the manufacture of acid-proof a1 oys makes it likely that a suitable material will soon be found, only external heating has been used in the operation hitherto. Internal heating by means of superheated steam has not been adopted because, agaimof the lack of suitable material.

By the present invention technical su1 phuric acid can be distilled to obtain chemically pure acid without any difliculty, by arranging electrical resistances as heating bodies Within the apparatus at suitable distance from the surface of the liquid. and

also suspendedboiling, which is particularly dangerous in the heating of sulphuric acid, is avoided.-

Internal heating makes possible the use of any suitable acid proof material for the con-- struction-of the acid container. Since the latter is not put under thermal strain, there is wide latitude for thickness of wall; the limit for the unit is thereby substantially extended and the heat consumption still more reduced. r

A further advantage of internal heating is that the matter which is always deposited owing to concentration during the distillation of technical sulphuric acid, does not settle on the heated surface, forming incrusta tions and thus increasing the difficulty of heating and interrupting the work, but collects in loose form on the bottom surface and may easily be removed by suitable devices during,the working.

It is a surprising fact that the distillation of technical sulphuric acid by means 0 internal electric resistance-heating, proceeds avcarries a dome-shaped cover d and wlth this is connected a delivery pipe eextending through a suitable condenser f. The heating elements 9 are arranged in the cover, for example all in the same plane, their ends 72, extending through, and packed in insulating manner in, thickened portions 11 of the cover. The level of the acid is kept constantly at the same and smallest possible distance from the heating elements, by means of suitable known dc vices. After the electric ci1rrent-alternat ing or continuous current may be used-has been switched on, distillation begins and proceeds quietly without interru tion'. The dis. tillate collected from the con enser is chemirally pure sulphuric acid.

When iron, for instance in the form of helices, is used for heating bodies the metal becomes coated with a thin layer of iron oxide and iron sulphate which prevents further attack on the metal and checks the decomposition of the H 80, vapour, which occurs in contact with glowing iron helices. For the concentration of the heat radiation on the surface of the liquid it is a suitable practice to place reflectors, for example quartz reflectors of semi-circular cross section, over the upper half of the heating bodies.

Now what I claim is 1. The process of distilling sulphuric acid, which comprises heating a body of the acid from an incandescent source of radiant heat above the surface of the acid. Y

2. The process of distilling sulphuric acid, which comprises heating a body of the acid in an inclosed acid-proof chamber by incandescent electrical heating bodies above the surface of the body of acid.

3. The process of distilling sulphuric acid,

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which comprises heating a body of acid in an inclined acid-proof chamber by incan-V descent electrical heating elements of nonacid-proof material above the surface of the acid body.

4. The process of distilling sulphuric acid, which comprises heating a body of the acid in an inclosed acid-proof chamber having a dome-shaped top reflector, by heat radiated from electrical heating means between the acid surface and reflector and augmented by reflected heat, while maintaining a constant acid level below the source of heat.

5. The process of distilling sulphuric acid, which comprises radiating heat onto the sur face of a body of acid contained in a closed chamber from a metallic electrical resistance heating element protected against the action of said acid by a coating of the reaction product of said metal and acid.

In testimony that I claim the foregoing as my invention, I have signed my name.

DR. GUSTAV BAUM. 

